The Water You Need Every Day from Food and Drinks

Because you don’t store water, you need to take in a new supply every day in your diet — enough to replace the nutrients and minerals you lose when you breathe, perspire, urinate, and defecate. On average, this amount adds up to 1,500 to 3,000 milliliters (50 to 100 ounces; 6 to 12.5 cups) a day.

Here’s where the water goes:

850 to 1,200 milliliters (28 to 40 ounces) is lost in breath and perspiration.

600 to 1,600 milliliters (20 to 53 ounces) is lost in urine.

50 to 200 milliliters (1.6 to 6.6 ounces) is lost in feces.

Toss in some extra ounces for a safe margin, and you get the current recommendations that women age 19 and up consume about 11 cups of water a day and men age 19 and up, about 15. But not all that water must come from the tap.

About 15 percent of the water that you need is created when you digest and metabolize food. The end products of digestion and metabolism are carbon dioxide and water composed of hydrogen from food and oxygen from the air that you breathe. The rest of your daily water comes directly from what you eat and drink.

You can get water from, well, plain water. Eight 10-ounce glasses give you 2,400 milliliters, approximately enough to replace what your body loses every day, so everyone from athletes to couch potatoes knows that a healthy body needs eight full glasses of water a day.

But who says that all that liquid has to come from water? Fruits and vegetables are full of water. Lettuce, for example, is 90 percent water. Furthermore, you get water from foods that you’d never think of as water sources: hamburger (more than 50 percent), cheese (the softer the cheese, the higher the water content — Swiss cheese is 38 percent water; skim milk ricotta, 74 percent), a plain, hard bagel (29 percent water), milk powder (2 percent), and even butter and margarine (10 percent). Only oils have no water.

In other words, a healthy adult in a temperate climate who isn’t perspiring heavily can get enough water simply by drinking only when he or she is thirsty, or by drinking water when drinking lots of coffee, tea, soft drinks, or alcohol.

Not all liquids are equally liquefying. The caffeine in coffee and tea and the alcohol in beer, wine, and spirits are diuretics, chemicals that make you urinate more copiously.